WO2024099948A1

WO2024099948A1 - Use of dimethylpyrazole phosphate in can type fertilizers

Info

Publication number: WO2024099948A1
Application number: PCT/EP2023/080810
Authority: WO
Inventors: Maarten Staal; Uwe Thiel; Markus Schmid; Manuel KNAUER
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2022-11-07
Filing date: 2023-11-06
Publication date: 2024-05-16
Anticipated expiration: 2025-05-07
Also published as: EP4615816A1

Abstract

The present invention therefore relates to use of dimethylpyrazole phosphate (DMPP) as a nitrification inhibitor in a solid fertilizer composition A comprising (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b) containing at least one of the following compounds: (b.1) magnesium carbonate, (b.2) calcium sulfate, (b.3) calcium magnesium carbonate, (b.4) and magnesium oxide, or a mixture of calcium carbonate with at least one of magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide, where the total amount of calcium carbonate, magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide is at least 90% by weight, in particular at least 95% by weight, based on the total weight of the component (b); wherein the total theoretical amount of magnesium carbonate and calcium sulfate provided by the components contained in the component (b) is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. The present invention also relates to a fertilizer composition comprising DMPP and the solid fertilizer composition A, and to a process for producing a fertilizer composition comprising the incorporation of DMPP into the fertilizer composition A.

Description

Use of dimethylpyrazole phosphate in CAN type fertilizers The present invention relates to use of dimethylpyrazole phosphate (DMPP) in solid fertilizer compositions A containing ammoniumnitrate and a salt selected form calcium carbonate, magnesium carbonate, calcium sulfate and combinations thereof. The present invention also relates to a fertilizer composition comprising DMPP and the solid fertilizer composition A, and to a process for producing a fertilizer composition comprising the incorporation of DMPP into the fertilizer composition A. BACKGROUND ON THE INVENTION Fertilizers are applied to soil or to plant tissues to supply the plant with nutrients including macro nutrients and micronutrients. For most modern agricultural practices, fertilization focuses on three main macro nutrients: Nitrogen (N), Phosphorus (P), and Potassium (K) with occasional addition of supplements like rock dust and micronutrients. An important class of fertilizers are nitrogen fertilisers which contain ammonia in bound form, because most plants are not able to absorb sufficient amounts of usable nitrogen from the environment (soil, air). Nitrogen fertilizers are made from ammonia (NH₃) produced by the Haber-Bosch process, which is used as a feedstock for all other nitrogen fertilizers, such as anhydrous ammonium nitrate (NH4NO3) and urea (CO(NH2)2). Calcium ammonium nitrate (CAN) fertilizers, also known as nitro-limestone or nitrochalk, is one of the widely used nitrogen fertilizer providing ammonium compound. CAN fertilizers can be considered as near-neutral in its effect on soil pH and therefore can be used on soils that have a low pH without lowering the pH further. CAN are nitrogen fertilisers which contains equal parts of fast acting nitrate-nitrogen and longer lasting ammonium-nitrogen and an inorganic component containing calcium minerals, typically limestone. This ensures a more continuous nitrogen supply to the crop and thus better efficiency of use, and also makes it suitable for unseasonal application during summer or winter. Ammonium compounds are converted microbially to nitrate (nitrification) in the soil within a relatively short time. Nitrate, however, can be leached from the soil. The leached fraction is no longer available for plant nutrition, and so for this reason rapid nitrification is undesirable. In order to prevent such loss of nitrate and exploit the fertilizer more effectively, nitrification inhibitors are added to it, which inhibit nitrifying microbes in the soil responsible for the conversion of ammonium (NH4⁺) into nitrate ( NO3-), to increase the residence time of NH₄ ⁺. The most widely researched commercial nitrification inhibitors are based on one of three compounds dicyandiamide (DCD, AlzChem AG), 2-chloro-6- (trichloromethyl)-pyridine (Nitrapyrin or N-Serve®, Dow Chemical Co.) and dimethylpyrazole phosphate, in particular 3,4-dimethylpyrazole phosphate, hereinafter also referred to as DMPP (CAS 202842-98-6). Besides other pyrazole based nitrification inhibitors such as 2-(N-3,4- dimethylpyrazole)succinic acid (hereinafter DMPSA) and 4-amino-1,2,4-triazole (hereinafter ATC), 3,4-dimethylpyrazole phosphate (DMPP) is highly efficient. Studies have shown that DMPP can significantly inhibit the conversion of ammonium in soil, showing significant nitrification inhibition effect, and far superior to similar products (Journal of Plant Nutrition and Fertilizer, 2017, 23, 54). Since its field application trials in Germany and Europe in 1999, it has been successfully commercialized and applied to agricultural production on a large scale. One problem attending the use of pyrazole compounds such as DMPSA and DMPP as nitrification inhibitors is their high volatility. When fertilizer preparations containing pyrazole compounds are stored, therefore, there is a continuous loss of active ingredient as a result of evaporation. For this reason the pyrazole compounds must be formulated in a nonvolatile form by means of appropriate measures. EP 1120388A1 describes phosphoric acid addition salts of 3,4-dimethylpyrazole and 4-chloro-3-methylpyrazole for use as nitrification inhibitors. Through the salt form it is possible for the volatility to be significantly reduced. To fix the pyrazole compounds in the fertilizer, they were converted, for example, into transition metal complexes such as zinc, copper or manganese complexes – see for example U.S. Pat. No.4,522,642. The volatility of the pyrazole compounds can thus be reduced. For environmental protection reasons, the widespread application of zinc, copper or manganese to the soil is, however, undesirable. Complexes of alkali metals or alkaline earth metals which are environmentally tolerable, are not adequately stable, however, and hydrolyze in the aqueous environment. It has furthermore been attempted by neutralization of the pyrazole compounds with mineral acids, such as phosphoric acid or hydrochloric acid, to decrease their volatility. DE 4128828A describes the use of nitrates and phosphates of 3-methylpyrazole for the coating of fertilizers. U.S. Pat. No.3,635,690 also describes the stabilization of pyrazole derivatives by mineral acids, such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. These acidic salts of the pyrazole compounds, however, may partly or completely dissociate into the pyrazole compound and salts of phosphoric acid under the high pH conditions present in CAN fertilizers. Dissociation, however results in increased volatility and loss of the pyrazole compound. To overcome this problem DE 4128828A suggests the sealing of the coated fertilizer with wax or oil. In the case of hygroscopic active compound salts, however, this process does not lead to a satisfactory resistance to hydrolysis. What is more, nitrification inhibitors based on the pyrazole compounds and at the same time suitable for CAN fertilizers have rarely been disclosed. WO 2015/086823A2 describes fertilizer mixtures comprising 2-(N-3,4-dimethylpyrazole)- succinic acid (DMPSA), which are based on calcium ammonium nitrate (CAN) mineral fertilizers, and also to a process for preparing DMPSA. The CAN fertilizers described therein generally contain 6 to 15% by weight, especially 10% of calcium, which equals concentrations of calcium carbonate of 15 to 37.5% by weight, especially 25% by weight. EP 4015489 discloses solid, particulate, ammonium based fertilizers containing an ammonium salt, a nitrification inhibitor, e. g. a 3,4-dimethylpyrazole derivative, such as DMPP or DMPSA, and an acidic compound in an amount of up to 5% by weight, and an anticaking and/or moisture repellent coating comprising a wax, a phosphate ester and an amine. The use of DMPP as nitrification inhibitor for CAN fertilizers and CAN type fertilizers has not been commercialized so far, probably because of the problem that DMPP is not stable on CAN. When used in CAN fertilizer, DMPP typically shows 30% degradation after 1 month storage at 20°C in closed vessels or gastight packages. For a commercial viable product, DMPP degradation should be less than 20% after 6 months storage at 20°C. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide inorganic nitrogen fertilizers, in particular CAN type fertilizers, which contain DMPP whose content does not significantly change during prolonged storage of the fertilizer. In particular, the fertilizers should be less susceptible to loss of ammonia caused by nitrification. Surprisingly, this object is achieved by use of DMPP in a solid fertilizer composition, especially a CAN-type fertilizer composition, in which at least a portion of calcium carbonate (CaCO3) of the inorganic component is replaced by calcium sulfate (CaSO4) and/or magnesium carbonate (MgCO3), such that the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition in anhydrous form. Surprisingly, such fertilizers show an increased stability of DMPP and reduced loss thereof, in particular during storage. Until now it was believed and asserted that DMPP would not be stable in CAN and CAN type fertilizers due to the high pH value of CAN fertilizers and CAN type fertilizers, which is typically above pH 6. Surprisingly, it was found that DMPP is stable on CAN fertilizer compositions and CAN type fertilizer compositions as described herein, which typically have a pH value of above pH 6, e. g. a pH ~7. The pH of the fertilizer composition remains nearly unchanged when at least certain amount of CaCO₃ is replaced with CaSO₄ and/or MgCO₃ in accordance with the present invention. In other words, the fertilizer composition according to the invention still has a pH value of ca. 7. However, the stability of DMPP increased significantly in the fertilizer composition according to the invention in spite of the pH of the fertilizer composition. Therefore, a first aspect of the present invention relates to the use of a composition (b) containing at least one of the following compounds: (b.1) magnesium carbonate, (b.2) calcium sulfate, (b.3) calcium magnesium carbonate (b.4) magnesium oxide, or a mixture of calcium carbonate with at least one of magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide, where the total amount of calcium carbonate, magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide is at least 95%, based on the total weight of the component (b); in a solid fertilizer composition A containing (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of the component (b): and dimethylpyrazole phosphate (DMPP) wherein the total theoretical amount of magnesium carbonate, magnesium oxide and calcium sulfate provided by the compounds contained in the component (b) is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form; for increasing the stability of DMPP in the fertilizer composition. Consequently, the loss of DMPP from the fertilizer composition is reduced. In a second aspect, the present invention relates to use of dimethylpyrazole phosphate (DMPP) as a nitrification inhibitor in a solid fertilizer composition A comprising (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b) containing at least one of the following compounds: (b.1) magnesium carbonate, (b.2) calcium sulfate, (b.3) calcium magnesium carbonate, (b.4) and magnesium oxide, or a mixture of calcium carbonate with at least one of magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide, where the total amount of calcium carbonate, magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide is at least 90% by weight, in particular at least 95% by weight, based on the total weight of the component (b); wherein the total theoretical amount of magnesium carbonate and calcium sulfate provided by the components contained in the component (b) is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. The use of the component (b) as defined herein in the solid fertilizer composition A, as defined herein, leads to an improved fixation and stability of DMPP in the fertilizer composition compared to conventional fertilizers compositions, where the inorganic component is limestone or another calcium carbonate. The volatility of DMPP is greatly reduced in this case, so that the storage stability of the fertilizer composition increases. Loss of DMPP during a storage period is avoided. Especially, the present invention is beneficial for application of DMPP in CAN and CAN type fertilizers. CAN and CAN type fertilizers are widely used fertilizers, but the conversion of ammonium to nitrate, when applied to the soil, results in N2O emissions and the formed nitrate can leach into ground water. The present invention enables DMPP, which is one of the most efficient nitrification inhibitors, to be applied to CAN and CAN type fertilizers and to reduce the N losses from CAN and CAN type fertilizers. Therefore, a third aspect of the present invention is a fertilizer composition comprising - 99 to 99.99% by weight, in particular 99.5 to 99.9% by weight, especially 99.6 to 99.8% by weight, based on the total weight of the fertilizer composition in anhydrous form, of a fertilizer composition A, as defined herein and hereinafter; and - 0.01 to 1% by weight, preferably 0.1 to 0.5% by weight, especially 0.2 to 0.4% by weight, based on the total weight of the fertilizer composition in anhydrous form, of DMPP. Further aspects of the invention relate to a process for producing a fertilizer composition, as defined herein and hereinafter, which comprises the incorporation of DMPP into a fertilizer composition A, as defined as defined herein and hereinafter. DETAILED DESCRIPTION OF THE INVENTION Solid fertilizer composition A Here and in the following, the term “CAN and CAN type fertilizer” refers to a solid fertilizer composition A. While according to EU2003-2003 standard the term “CAN fertilizer” refers to a ammonium nitrate fertilizer wherein the total amount of calcium carbonate and magnesium carbonate is at least 20% by weight, based on the total weight of the fertilizer, the term CAN type fertilizer refers to a fertilizer, where the proportion of the total amount of calcium carbonate and magnesium carbonate is lower than 20% by weight. In accordance with the invention, the solid fertilizer composition A comprises 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a). Ammonium nitrate (NH₄NO₃) may be prepared by any suitable methods known to skilled person in the art, for example by reacting ammonia gas with nitric acid in water. The water must be then removed from the ammonium nitrate aqueous solution to yield solid ammonium nitrate, most often by evaporation. Ammonia is most often prepared from atmospheric nitrogen, while nitric acid is prepared from the combustion of ammonia, and so ammonium nitrate is most conveniently manufactured where ammonia is made. In the context of the present invention, the pH of the solid fertilizer composition is the pH of a 10% by weight aqueous solution of the fertilizer. The solid fertilizer composition A further comprises 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of the component (b). According to the invention, the component (b) of the fertilizer composition contains at least one of compound selected from the group consisting of magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide, or a mixture of two or more of said compounds. Besides magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide, the component (b) may contain calcium carbonate (CaCO₃). Preferably, the component (b) does not contain more than 80% by weight, in particular not more than 65% by weight, especially not more than 50% by weight of calcium carbonate, based on the total weight of the component (b). The amount of calcium carbonate in component (b) may be as low as 0% by weight or not more than 10% by weight, based on the total weight of the component (b). Preferably, the amount of calcium carbonate chosen such that it is less than 18% by weight, in particular less than 16% by weight, more particularly less than 15% by weight, especially at most or less than 12% by weight and may be as low as 0% by weight, based in each case on the total weight of the fertilizer composition A in anhydrous form. In preferred fertilizers, the composition A comprises 0 to 17.9% by weight or 1 to 17.9% by weight, in particular 0 to 15.9% by weight or 2 to 15.9% by weight, in particular 0 to 14.9% by weight or 2 to 14.9% by weight, especially 0 to 12% by weight or 1 to 12% by weight of calcium carbonate, based on the total weight of the fertilizer composition A in anhydrous form. Here and in the following, any amounts given for calcium carbonate, magnesium carbonate and calcium sulfate refer to the anhydrates of these salts and are based on the total weight of the component (b), if not stated otherwise. The total theoretical amount of magnesium carbonate (MgCO₃) and calcium sulfate (CaSO₄) provided by the components/constituents of component (b) is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. The theoretical amount of magnesium carbonate is understood as the stoichiometric proportions of Mg and carbonate (CO₃) present in the component (b) which correspond to the formula MgCO3. The theoretical amount of calcium sulfate is understood as the stoichiometric proportions of Ca and sulfate (SO4) present in the component (b) which correspond to the formula CaSO₄. It is important to note that the component (b) may be pure components or a mixture of its constituents, provided that the theoretical amount of magnesium carbonate and calcium sulfate in the fertilizer composition is fulfilled. For example, the component (b) may be selected from the following constituents or mixtures of constituents, hereinafter compositions (i) to (xii): (i) magnesium carbonate; (ii) calcium sulfate; (iii) mixtures of magnesium carbonate with calcium sulfate, (iv) mixtures of magnesium carbonate with calcium carbonate, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b), (v) mixtures of magnesium oxide with calcium carbonate, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b), (vi) mixtures of calcium carbonate with calcium sulfate, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b); (vii) mixtures of magnesium carbonate with calcium carbonate and calcium sulfate, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b); (viii) mixtures of calcium magnesium carbonate, e. g. in the form of dolomite, and calcium sulfate, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b); (ix) mixtures of magnesium oxide with calcium carbonate and calcium sulfate, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b); (x) mixtures of magnesium carbonate with calcium carbonate and magnesium oxide, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b); (xi) mixtures of calcium magnesium carbonate with calcium sulfate and magnesium oxide, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b); and (xii) mixtures of magnesium carbonate with calcium carbonate, calcium sulfate and magnesium oxide, where the amount of calcium carbonate is in particular not more than 80% by weight and especially not more than 50% by weight, e.g.1 to 80% by weight, especially 4 to 50% by weight, based on the total weight of component (b). In the aforementioned compositions (i)-(xii), the total amount of the mentioned compounds is in particular at least 90% by weight, especially at least 95% by weight or at least 99% by weight, based on the total weight of the respective compositions (i)-(xii). In the compositions (iv) to (xii), which comprise calcium carbonate, the weight ratio of calcium carbonate, including the calcium carbonate contained in dolomite, to the total weight of the other compounds, i. e. magnesium carbonate, including the magnesium carbonate contained in dolomite, magnesium oxide and calcium sulfate, is in particular in the range of 1:20 to 1:1. Amongst the compositions (i)-(xii), preference is given to components (b), which are selected from compositions (i), (ii), (iii) and (iv), where in the composition (iv) the weight ratio of calcium carbonate to magnesium carbonate is in particular in the range of 1:1 to 1:20. In the preferred composition (i), the amount of magnesium carbonate is preferably at least 90% by weight, in particular at least 95% by weight. In the preferred composition (ii), the amount of calcium sulfate is preferably at least 90% by weight, in particular at least 95% by weight. In the preferred composition (iii), the total amount of calcium sulfate and magnesium carbonate is preferably at least 90% by weight, in particular at least 95% by weight. In the preferred composition (iv), the total amount of calcium carbonate and magnesium carbonate is preferably at least 90% by weight, in particular at least 95% by weight. The composition (b), in particular the compositions (i) to (xii), especially the preferred compositions (i) to (iv) may additionally contain further constituents, which are different from magnesium carbonate, calcium sulfate, calcium carbonate and calcium magnesium carbonate, in amounts of up to 10% by weight, in particular up to 5% by weight, based on the total amount of the respective composition (b) or (i) to (xii), respectively. These further constituents are typically minerals which are suitable as inert inorganic components of fertilizer compositions which may be contained in minerals used as constituents of the composition in CAN type fertilizers. For example, such further constituents include silicates, alumosilicates, alumina, calcium oxide, calcium hydroxide, magnesium oxide, alkalimetal phosphate and alkalimetal hydrogen phosphates, or mixtures thereof. In particular, the component (b) may contain up to 10% by weight, in particular up to 5% by weight of magnesium oxide, based on the total weight of the component (b). Principally, any magnesium carbonate can be used in the component (b) of the fertilizer composition. Usually, naturally occurring magnesium carbonate will be used. Typically, magnesium carbonate occurs in nature in large quantities as magnesite (bitter spar) (MgCO₃) with a hardness of 4-4½. Along with dolomite (CaMg(CO₃)₂), it is the most important magnesium mineral. Also known are the minerals barringtonite MgCO3·2H2O, nesquehonite (MgCO3·3H2O) and lansfordite (MgCO3·5H2O). Any of these minerals can be used as a magnesium carbonate for the purpose of the invention. A combination of MgO with calcium carbonate can be used as a source of magnesium carbonate, optionally in combination with further magnesium carbonate, as long as the amount of Ca and Mg is such that the theoretical amounts of magnesium carbonate and calcium carbonate is as defined herein. Magnesium carbonate can also be used in the form of dolomite, as long as the theoretical amount of MgCO3 contributed by dolomit and any other source of magnesium carbonate is as defined herein. A combination of MgO with one of magnesium carbonate, calcium magnesium carbonate and calcium sulfate may also be used. If the component (b) contains magnesium oxide, the amount of MgO is preferably in the range of 0.1 to 5 % by weight, based on the total weight of the fertilizer composition A in anhydrous form. Principally, any calcium sulfate can be used in the fertilizer composition. Usually, naturally occurring calcium sulfate will be used. Typically, calcium sulfate occurs naturally in the form of the minerals anhydrite CaSO4, gypsum Ca[SO4]·2H2O (dihydrate) and bassanite Ca[SO4]·½H2O (hemihydrate) in evaporites. Any of these minerals can be used as a magnesium carbonate for the purpose of the invention. Principally, any calcium carbonate can be used in the fertilizer composition. Usually, naturally occurring calcium carbonate will be used. Typically, calcium carbonate is found frequently in geologic settings and constitutes an enormous carbon reservoir. Calcium carbonate occurs as aragonite, calcite and dolomite as significant constituents of the calcium cycle. The carbonate minerals form the rock types are limestone, chalk, marble, travertine, tufa, and others. Any of these minerals can be used as a magnesium carbonate for the purpose of the invention. Principally, any magnesium oxide can be used in the fertilizer composition. The magnesium oxide may be naturally occurring magnesium oxide, such as periklas, or industrially produced magnesium oxide, including calcined magnesit or calcined magnesium hydroxide. As mentioned before, calcium carbonate can also be used in the form of dolomite, as long as the amount of calcium carbonate contributed by dolomite and any further calcium carbonate is as defined herein. In a preferred group (1) of embodiments, the component (b) comprises magnesium carbonate. In a subgroup (1-a) of this preferred group (1) of embodiments the component (b) comprises at least 90%, particularly at least 95%, preferably at least 99% by weight, especially 100%, based on the total weight of the component (b), of magnesium carbonate. In another preferred subgroup (1-b) of this preferred group (1) of embodiments, the component (b) is a mixture comprising magnesium carbonate and calcium sulfate. In this mixture, the weight ratio of magnesium carbonate to calcium sulfate is generally in the range of 1:40 to 40:1, preferably in the range of 1:30 to 30:1, especially in the range of 1:21 to 21:1. Preferably, the mixture of subgroup (1-b) does not contain more than 10%, in particular not more than 5% by weight or not more than 1% by weight, based on the total weight of component (b), of calcium carbonate. In another preferred group of embodiments (2), the component (b) is selected from mixtures comprising calcium carbonate and at least one of magnesium carbonate and calcium sulfate, in particular from mixtures comprising calcium carbonate and magnesium carbonate and optionally calcium sulfate. In a subgroup (2-a) of this preferred group (2) of embodiments the, the component (b) is selected from mixtures comprising calcium carbonate and at least one of magnesium carbonate and calcium sulfate, in particular from mixtures comprising calcium carbonate and magnesium carbonate and optionally calcium sulfate, such as mixtures of calcium carbonate and calcium sulfate and mixtures of calcium carbonate, magnesium carbonate and calcium sulfate. In this subgroup (2-a), the weight ratio of calcium carbonate to the total weight of calcium sulfate and magnesium carbonate is generally in the range of 1:20 to 10:1 and frequently in the range of 1:15 to 5:1. High contents of MgCO3 are preferred. Therefore, in a preferred group of embodiments the weight ratio of calcium carbonate to the total weight of calcium sulfate and magnesium carbonate is in the range of 1:20 to 1:1, in particular in the range of 1:15 to 1:2, more preferably in the range of 1:12 to 1:5. In these mixtures of the subgroup (2-a) the relative amount of calcium carbonate is preferably chosen such that the fertilizer composition A comprises calcium carbonate in an amount of 1 to 17.9% by weight, in particular 1 to 15.9% by weight, more particularly 1 to 14.9% by weight and especially 1 to 12% by weight, based on the total weight of the fertilizer composition A in anhydrous form. Especially, the component (b) is a mixture of calcium carbonate and magnesium carbonate, where the total amount of is at least 99% of the mixture. This group of embodiments is referred to as subgroup (2-b). In this subgroup (2-b), the weight ratio of calcium carbonate to magnesium carbonate is generally in the range of 1:20 to 10:1 and frequently in the range of 1:15 to 5:1. High contents of MgCO₃ are preferred. Therefore, in a preferred group of embodiments the weight ratio of calcium carbonate to magnesium carbonate is in the range of 1:20 to 1:1, in particular in the range of 1:15 to 1:2, more preferably in the range of 1:12 to 1:5. In these mixtures of the subgroup (2-b) the relative amount of calcium carbonate is preferably choses such that the fertilizer composition A comprises calcium carbonate in an amount of 1 to 17.9% by weight, in particular 2 to 15.9% by weight, more particularly 1 to 14.9% by weight and especially 1 to 12% by weight, based on the total weight of the fertilizer composition A in anhydrous form. Preferably, the solid fertilizer composition A comprises (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b) which is according to group (1) of embodiments, wherein the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. More particularly, the solid fertilizer composition A comprises (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b), which is according to subgroup (1-a) or (1-b) of embodiment (1), wherein the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. Especially, the solid fertilizer composition A comprises (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b), which is according to subgroup (1-b) of embodiment (1), wherein the weight ratio of magnesium carbonate to calcium sulfate is generally in the range of 1:40 to 40:1, preferably in the range of 1:30 to 30:1, especially in the range of 1:21 to 21:1, wherein the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. Preferably, the solid fertilizer composition A comprises (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b), which is according to group (2) of embodiments, wherein the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, and where the weight ratio of calcium carbonate to the total weight of calcium sulfate and magnesium carbonate is preferably in the range of 1:20 to 1:1, in particular in the range of 1:15 to 1:2, especially in the range of 1:12 to 1:5. More preferably, the solid fertilizer composition A comprises (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b), which is according to subgroups (2-a) or (2-b) of embodiment (2), wherein the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form , and where the weight ratio of calcium carbonate to the total weight of calcium sulfate and magnesium carbonate is preferably in the range of 1:20 to 1:1, in particular in the range of 1:15 to 1:2, especially in the range of 1:12 to 1:5. Especially, the solid fertilizer composition A comprises (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b), which is according to subgroup (2-b) of embodiment (2), wherein the weight ratio of calcium carbonate to magnesium carbonate is generally in the range of 1:20 to 10:1, frequently in the range of 1:15 to 5:1, preferably in the range of 1:20 to 1:1, in particular in the range of 1:15 to 1:2, especially in the range of 1:12 to 1:5, wherein the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. The composition A may further contain up to 15% by weight, preferably up to 10% by weight, especially up to 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of further ingredients. Further ingredients are for example trace elements, further minerals, standardizers, binders, and the like. The water fraction in the composition A is preferably not more than 1.0% by weight, more preferably not more than 0.5% by weight, more particularly not more than 0.3% by weight, based on the total weight of the fertilizer composition A in anhydrous form, and is therefore negligible in the balance of quantities. Here the water fraction refers to free water, i. e. to water which is not bound in the crystalline materials of component (b), i.e. which is not hydrate water crystalline materials of component (b). The nitrogen content of the composition A in anhydrous form is preferably 20% by weight, more preferably at least 22% by weight, very preferably in the range of 25 to 29% by weight, especially in the range of 26 to 28% by weight, based on the total weight of the fertilizer composition A in anhydrous form. The composition A comprises frequently in the range of 22 to 28% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of nitrogen, in which case, for example, there may be 13.5% by weight of fast-acting nitrate nitrogen and 13.5% by weight of slow-acting ammonium nitrogen, based on the total weight of the fertilizer composition A in anhydrous form. The composition A may essentially consist of the aforementioned components (a) and (b) or may comprise further components. Frequently, the amount of the components (a) and (b) is at least 85% by weight, in particular at least 90% by weight and especially at least 95% by weight, based on the total weight of the composition A, except for water. In this context, the term “essentially consists” means that the total amount of the aforementioned components (a) and (b) is at least 98% by weight, based on the total weight of the composition A, except for water. Further constituents include, for example, trace elements, micronutrients, such as boron compounds, and salts of zinc, molybdenum, manganese, copper or iron, further minerals, standardizers and binders. Furthermore, according to one embodiment of the invention, the composition A may comprise in the range of 0.1 to 1% by weight, preferably in the range of 0.1 to 0.5% by weight, more particularly in the range of 0.15 to 0.3% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of boron as element and/or in the form of boron compounds. The solid fertilizer composition A can be dissolved in water and may be in form of an aqueous solution. Particularly, pH value of the aqueous solution of the fertilizer composition A is greater than 6, preferably greater than 6.3, especially greater than or equal to 6.5. In a particularly preferred group of embodiments, the composition of A is calcium ammonium nitrate (CAN) mineral fertilizer, which contains at least one of magnesium carbonate and calcium sulfate, where the total amount of magnesium carbonate and calcium sulfate is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form, e. g. from 3 to 40% by weight, preferably from 4 to 35% by weight and especially from 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form. The composition A of the invention, customarily has a water content in the range of 0.1 to 0.5% by weight, preferably in the range of 0.1 to 0.2% by weight, more particularly in the range of 0.15% by weight, based on the total weight of the fertilizer composition A. DMPP According to the invention, dimethylpyrazole phosphate is used as a nitrification inhibitor in a solid fertilizer composition A, as defined herein. Here and in the following, the abbreviation DMPP refers to dimethylpyrazole phosphate, in particular to 3,4-dimethylpyrazole phosphate (CAS 202842-98-6). DMPP is typically the 1:1 adduct of dimethylpyrazole and phosphoric acid and has the molecular formula C5H8N2*H3PO4. A liquid formulation of DMPP is commercially available as Vibelsol® of BASF SE) In principle, DMPP comprises or is 3,4-dimethylpyrazole phosphate. Typically, the content of 3,4-dimethylpyrazole phosphate in commercially available DMPP is at least 90%, based on the total weight of dimethylpyrazole phosphate present in the commercially available DMPP. DMPP may be prepared by any suitable methods, which are known to a skilled person in the art. Preparation methods of 3,4-dimethylpyrazole and 3,4-dimethylpyrazole phosphate (DMPP) are described for example in CN 110218188A, US 6022979A, US 6229022B, EP-B-0917526 or EP-B-1120388. For further suitable preparation methods, reference may also be made to EP-B-0974585 and EP-B-2748148. The preparation may also be analogous to EP-A-0529473 or EP-B-0516982. Preparation is accomplished preferably by reaction of 3,4-dimethylpyrazole with ortho-phosphoric acid. For the preparation of 3,4-dimethylpyrazole, reference may also be made to Noyce et al., Jour. of Org. Chem. 20, 1955, pages 1681 to 1682. Reference may further be made to EP 0474037A1, US 5047551A, and EP 0467707A1, and also to EP 1120388A1. For the purification of the 3,4-dimethylpyrazole, reference may be made to EP 2748148A1. For incorporation of the DMPP into the composition A, DMPP may be used in solid or preferably in liquid form, i. e. dissolved in a suitable solvent, such as water. In most preferred group of embodiments, DMPP is used in the form of an aqueous solution. In the aqueous solution, the concentration of DMPP in the aqueous solution of DMPP is preferably in the range of 20 to 45% by weight, preferably in the range of 25 to 40% by weight, more preferably in the range of 27.5 to 36% by weight, based on the total weight of the solution of DMPP. Particular preference is given to using DMPP as an aqueous solution having a pH in the range of 1 to 5, especially in the range of 1 to 3. By adding phosphoric acid and/or one or more phosphates or polyphosphates to the aqueous solution of DMPP, the water fraction of the aqueous solution can be reduced and the stability of the aqueous solution can be further improved. Examples of phosphates contemplated are Na₂HPO₄, Na₃PO₄, K₂HPO₄, K₃PO₄, diammonium phosphate or calcium ammonium phosphate. Using DMPP in the composition A, as defined herein, in accordance with the present invention, the amount of DMPP is in the range of 0.01 to 0.2% by weight, preferably in the range of 0.05 to 0.16% by weight, especially in the range of 0.1 to 0.14% by weight, based on the total weight of the fertilizer composition A in anhydrous form. Application of DMPP as nitrification inhibitor in the composition A, as defined herein, preferably in the composition A, which is a CAN fertilizer, takes place according to the generally customary processes. For example a liquid formulation of DMPP is sprayed onto composition A, in particular to granules thereof, and subsequently mixed to obtain a homogeneous distribution of DMPP on composition A. Fertilizer composition and production process As mentioned above, the use of DMPP as a nitrification inhibitor in a solid fertilizer composition A, as defined herein, is associated with the unexpected benefits. The fertilizer compositions according to the invention comprise - 99 to 99.99% by weight, in particular 99.5 to 99.9% by weight, especially 99.6 to 99.8% by weight, based on the total weight of the fertilizer composition in anhydrous form, of a fertilizer composition A, as defined herein; and - 0.01 to 0.2% by weight, preferably 0.05 to 0.16% by weight, especially 0.1 to 0.14% by weight, based on the total weight of the fertilizer composition in anhydrous form, of DMPP. The solid fertilizer composition of the present invention can be produced by analogy to fertilizer compositions. Such processes comprise the incorporation of DMPP into the fertilizer composition A, as defined herein the required amounts. Preferably, the amount of DMPP used for producing the inventive fertilizer composition is in the range of 0.05 to 0.16% by weight, especially 0.1 to 0.14% by weight, based on the total weight of the fertilizer composition in anhydrous form. The inventive fertilizer composition may also include small amounts of water, as for example in the range of 0.1 to 0.2% by weight, based on the total weight of the fertilizer composition including water. Large amounts of water in the fertilizer composition ought to be avoided. The inventive fertilizer composition may be produced, for example, according to the following method: For the production of the fertilizer composition of the invention, the solid fertilizer composition A, which is preferably calcium ammonium nitrate mineral fertilizer, can be applied with DMPP in any suitable manner, for example by spray application, drum application or impregnation. The method is known, for example, from EP 0529473A1, hereby referenced in full. Such application methods involve mechanical movement of the composition A to homogenize the application, for example by means of stirrers or by movement of the composition A for example in a drum. After DMPP has been applied, the composition A is dried in order to remove the moisture introduced with the mixture. The drying is preferably effected up to such a level of dryness that caking or dissolution of the composition A is reliably prevented. In practice, it is advantageous to store coated or impregnated composition A for several days. By contrast with DE-C-10164103, no heating of the fertilizer is needed on application. The coated or impregnated composition A may be further treated with e.g. anti-caking or anti-dust treatments. The solid fertilizer composition A may be in form of granulates, powders, chips, tablets or extrudates. Particular preference is given to granulates. Thereby, the fertilizer compositions are obtained in the form of a granulate. Typical particle sizes of these granules may be in the range of 1 to 8 mm, in particular in the range of 1.5 to 6 mm. The particle size refers to the size of at least 90% by weight of the granules contained in the granulate. It can be determined by sieving. DMPP may also be added during the production of the granulate, e. g. by incorporating the DMPP in to the mass subjected to granulation. The fertilizer compositions of the invention may be applied to the soil or to the plant tissue. The amount of the fertilizer composition applied will require on the demands of the plant. The fertilizer composition of the invention is typically applied as solid fertilizer. EXAMPLES The invention is elucidated in more detail by the examples hereinafter. 1. Experimental setup Materials used for producing the fertilizer compositions: CAN and CAN type fertilizer The CAN fertilizer granulates and CAN type fertilizer granulates used in the following examples are commercially available products. Prior to their treatment with DMPP they were analyzed with respect to their elemental composition as described below. All fertilizer samples were solid granules with an average particle size between 1 – 5 mm. Nitrification inhibitor (DMPP) A DMPP containing nitrification inhibitor commercially available from BASF as Vibelsol®. 2. Fertilizer treatment 4 kg CAN fertilizer granules were added to a rotating disk mixer. While mixing, 15 g Vibelsol® formulation is sprayed onto the fertilizer granules using a syringe. After 3 minutes mixing time, the treated fertilizer granules were transferred from the mixer into a stainless steel bowl and dried overnight at room temperature. Afterwards, a sample was taken for active ingredient analysis and the remainder of the treated fertilizer was filled in 100 mL polyethylene bottles (100 g fertilizer per bottle). The bottles were closed and stored at 40 °C. After 1 and 2 months samples were taken for active ingredient (DMPP) analysis. Active ingredient recovery was calculated by dividing the measured DMPP concentration by the DMPP concentration measured before storage. 3. Analytics 3.1 Active ingredient analysis For active ingredient analysis, two samples of 15 g fertilizer were dissolved in 100 mL of demineralized water (Milli-Q) respectively and analyzed according to HPLC method DIN EN 16328. The resulting active ingredient concentrations were averaged. 3.2 Elemental analysis Ca and Mg contents of fertilizer samples were determined using DIN EN ISO 11885:2009- 09. S content was determined using VO(EG)2003/2003, Annex IV, B8.1, 8.9:2003-11, ammonium-nitrogen content was determined using VO(EG)2003/2003, Annex IV, B2.1:2003-11, nitrate-nitrogen content was determined via VDLUFA MB Bd. II, 3.4.1:1995, total nitrogen content was determined using VDLUFA MB Bd.II.1,3.5.2.7:1995 or calculated by addition of the nitrate- and ammonium-nitrogen contents. 3.3 pH measurement pH measurements of the untreated fertilizer were performed on solutions of 10 g fertilizer dissolved in 90 g water, using a pH meter (KNICK pH-Meter 766 with SI Analytics, BlueLine 18 electrode). 3.4 Carbonate test The presence of carbonates in the fertilizer samples was determined according to method VDLUFA I, A5.3.1:1991. The emitted amount of CO₂ during the test was expressed in weight percent based on the total weight of the fertilizer. 4. Examples and results 4.1 Characterization of the untreated fertilizer samples 1 to 5 Prior to the treatment with the DMPP containing nitrification inhibitor (Vibelsol®), the untreated CAN fertilizer samples 1 to 5 were analyzed for their pH values, for presence of carbonates and for the contents of N, Ca, Mg and S. Based on the results of the elemental analysis and carbonate test the content of ammoniumnitrate (AN), calcium carbonate (CaCO3), magnesium oxide (MgO), magnesium carbonate (MgCO3) and calcium sulfate (CaSO₄) were calculated according to their molecular weight. The measured and calculated contents are expressed in weight percent based on the total weight of the fertilizer. The following table summarizes the pH values, the analyzed mineral contents, calculated contents of AN, CaCO₃, MgCO₃, MgO and CaSO₄ of the fertilizer samples 1 to 5. 4.2 Fertilizer treatment with the nitrification inhibitor and storage The untreated fertilizer samples 1 to 5 were treated with Vibelsol® and stored in closed bottles at 40 °C for 1 and 2 months, respectively. After the storage, the amount of active ingredient DMPP was analyzed using HPLC. Active ingredient recovery was calculated by dividing the measured DMPP concentration by the DMPP concentration measured before storage. The results in table 2 show that, surprisingly, a good DMPP stability is achieved with CAN samples containing less than 15 wt.-% CaCO3.

Table 1 01W O 01

Table 2 22

*from Table 1

Claims

Claims 1. The use of a composition (b) containing at least one of the following compounds: (b.1) magnesium carbonate, (b.2) calcium sulfate, (b.3) calcium magnesium carbonate, (b.4) magnesium oxide, or a mixture of calcium carbonate with at least one of magnesium carbonate, cal- cium sulfate, calcium magnesium carbonate and magnesium oxide, where the total amount of calcium carbonate, magnesium carbonate, calcium sul- fate, calcium magnesium carbonate and magnesium oxide is at least 95%, based on the total weight of the component (b); in a solid fertilizer composition A containing (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhy- drous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of the component (b): and dimethylpyrazole phosphate (DMPP), wherein the total theoretical amount of magnesium carbonate, magnesium oxide and calcium sulfate provided by the compounds contained in the component (b) is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form; for increasing the stability of DMPP in the fertilizer composition. 2. Use of dimethylpyrazole phosphate (DMPP) as a nitrification inhibitor in a solid fer- tilizer composition A comprising (a) 60 to 97% by weight, preferably 65 to 96% by weight, especially 66 to 95% by weight, based on the total weight of the fertilizer composition A in anhy- drous form, of ammonium nitrate as component (a); and (b) 3 to 40% by weight, preferably 4 to 35% by weight, especially 5 to 34% by weight, based on the total weight of the fertilizer composition A in anhydrous form, of a component (b) containing at least one of the following compounds: (b.1) magnesium carbonate, (b.

2) calcium sulfate, (b.3) calcium magnesium carbonate, (b.4) magnesium oxide, or a mixture of calcium carbonate with at least one of magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide, where the total amount of calcium carbonate, magnesium carbonate, calcium sulfate, calcium magnesium carbonate and magnesium oxide is at least 95%, based on the total weight of the component (b); wherein the total theoretical amount of magnesium carbonate, magnesium oxide and calcium sulfate provided by the compounds contained in the component (b) is at least 3% by weight, preferably at least 4% by weight, especially at least 5% by weight, based on the total weight of the fertilizer composition A in anhydrous form.

3. The use according to claim 1 or claim 2, wherein the component (b) comprises magnesium carbonate.

4. The use according to any one of the preceding claims, where the component (b) does not contain more than 80% by weight, especially not more than 50% by weight of calcium carbonate, based on the total weight of the component (b).

5. The use according to any one of preceding claims, wherein the component (b) is selected from magnesium carbonate, calcium sulfate, and mixtures comprising cal- cium carbonate and at least one of magnesium carbonate and calcium sulfate, in particular from mixtures comprising calcium carbonate and magnesium carbonate and optionally calcium sulfate, where in the mixtures comprising calcium carbonate the weight ratio of calcium carbonate to the total weight of magnesium carbonate and calcium sulfate is in the range of 1:20 to 1:1.

6. The use according to any one of the preceding claims, where the component (b) is characterized by one of the following features a), b), c) or d) a) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of magnesium carbonate; b) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of calcium sulfate; c) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of mixtures of magnesium carbonate and calcium sulfate; d) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of mixtures of magnesium carbonate and calcium carbonate, where the weight ratio of calcium carbonate to magnesium carbonate is in the range of 1:1 to 1:20.

7. The use according to any one of preceding claims, wherein the total amount of magnesium carbonate and calcium sulfate is in the range of 3 to 40% by weight, in particular, in the range of 4 to 35% by weight, based on the total weight of the ferti- lizer composition A in anhydrous form.

8. The use according to any one of preceding claims, wherein the fertilizer composi- tion A contains less than 18% by weight, in particular less than 15% by weight, es- pecially at most or less than 12% by weight, based on the total weight of the ferti- lizer composition A in anhydrous form, of calcium carbonate.

9. The use according to any one of preceding claims, wherein pH value of an aque- ous solution of the fertilizer composition A is greater than 6, preferably greater than 6.3, especially greater than or equal to 6.5.

10. The use according to any one of preceding claims, wherein the amount of DMPP is in the range of 0.01 to 0.2% by weight, preferably in the range of 0.05 to 0.16% by weight, especially in the range of 0.1 to 0.14% by weight, based on the total weight of the fertilizer composition A in anhydrous form.

11. The use according to any one of preceding claims, wherein DMPP comprises or is 3,4-dimethylpyrazole phosphate.

12. The use according to any one of preceding claims, wherein DMPP is used in the form of an aqueous solution.

13. The use according to claim 12, wherein the concentration of DMPP in the aqueous solution of DMPP is in the range of 20 to 45% by weight, based on the total weight of the solution of DMPP. 14. A fertilizer composition comprising - 99 to 99.99% by weight, in particular 99.5 to 99.9% by weight, especially 99.6 to 99.8% by weight, based on the total weight of the fertilizer composi- tion in anhydrous form, of a fertilizer composition A according to claims 1 to 8; and - 0.01 to 0.2% by weight, preferably 0.05 to 0.16% by weight, especially 0.1 to 0.

14% by weight, based on the total weight of the fertilizer composition in an- hydrous form, of DMPP.

15. A process for producing a fertilizer composition according to claim 14, which com- prises the incorporation of DMPP into a fertilizer composition A, as defined accord- ing to claims 1 to 9. 16. The composition of claim 14 or the process of claim 15, wherein the amount of DMPP is 0.05 to 0.

16% by weight, especially 0.1 to 0.14% by weight, based on the total weight of the fertilizer composition in anhydrous form.

17. The composition or process of any one of claims 14 to 16, wherein the fertilizer composition A is in form of a granulate.

18. The composition or the process of claim 17, wherein the fertilizer composition A is coated or impregnated with DMPP.

19. The composition or process of any one of claims 14 to 18, where the component (b) does not contain more than 80% by weight, in especially not more than 50% of calcium carbonate, based on the total weight of the component (b).

20. The composition or process of any one of claims 14 to 19, where the component (b) is selected from magnesium carbonate and mixtures comprising calcium car- bonate and at least one of magnesium carbonate and calcium sulfate, in particular from mixtures comprising calcium carbonate and magnesium carbonate and op- tionally calcium sulfate, where in the mixtures comprising calcium carbonate the weight ratio of calcium carbonate to the total weight of magnesium carbonate and calcium sulfate is in the range of 1:20 to 1:1.

21. The composition or process of any one of claims 14 to 20, where the component (b) is characterized by one of the following features a), b), c) or d) e) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of magnesium carbonate; f) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of calcium sulfate; g) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of mixtures of magnesium carbonate and calcium sulfate; h) the component (b) comprises at least 90% by weight, based on the total weight of component (b) of mixtures of magnesium carbonate and calcium carbonate, where the weight ratio of calcium carbonate to magnesium carbonate is in the range of 1:1 to 1:20.

22. The composition or process of any one of claims 14 to 21, where the total amount of magnesium carbonate and calcium sulfate is in the range of 3 to 40% by weight, in particular, in the range of 4 to 35% by weight, based on the total weight of the fertilizer composition A in anhydrous form.

23. The composition or process of any one of claims 14 to 22, where the fertilizer com- position A contains less than 18 % by weight, in particular less than 15% by weight, especially less than 12 % by weight, based on the total weight of the ferti- lizer composition A in anhydrous form, of calcium carbonate.

24. The composition or process of any one of claims 14 to 23, where the pH value of an aqueous solution of the fertilizer composition A is greater than 6, preferably greater than 6.3, especially greater than or equal to 6.5.

25. The composition or process of any one of claims 14 to 24, where the amount of DMPP is in the range of 0.01 to 0.2% by weight, preferably in the range of 0.05 to 0.16% by weight, especially in the range of 0.1 to 0.14% by weight, based on the total weight of the fertilizer composition A in anhydrous form.

26. The composition or process of any one of claims 14 to 25, where DMPP comprises or is 3,4-dimethylpyrazole phosphate.